ATLANTA — Things could not have gone much worse during the first week of the season for the Marlins. And then Sunday happened.

Not only did the Marlins cap a six-game, season-opening home stand with their fifth loss, 8-5 to the lowly Rays, but their opening day starter and 2014 All-Star, Henderson Alvarez, felt enough discomfort in his arm that he will undergo an exam on his elbow today.

The Miami Herald was the first to report that Alvarez would have the MRI.

Alvarez (0-2) allowed four runs in five innings, just the second time since July 24 he didn’t go at least six innings.

Alvarez’s fastball velocity, which is typically around 93 mph, was down to around 90 mph Sunday.

Losing the right-handed Alvarez would be a major blow to a team that believes it can take that next jump into wild card contention. He was a savior last season after Jose Fernandez underwent Tommy John surgery in May, finishing with the sixth best ERA in the NL (2.65) along with a 12-7 record. He threw 187.0 innings, which was one/third short of his career high in 2012 while with Toronto.

The Marlins also suffered two key losses to their bench when backup catcher Jeff Mathis and utility infielder Don Kelly both fractured their right ring fingers. Mathis believes he’ll miss 4-to-6 weeks. Kelly will be examined by a hand specialist.

“We talked about keeping guys healthy all spring and we were able to do it,” manager Mike Redmond said Sunday. “It’s one of those things in baseball that happens. Unfortunately, it happened on the same day to two guys. We’ve got to be able to pick up, patch it together and move on.”

The Marlins will announce two corresponding moves for Mathis and Kelly today as they start a 10-game road trip with three games in Atlanta. J.T. Realmuto could be called up from Class AAA New Orleans to replace Mathis. Reid Brignac and Jordany Valdespin were the final two infielders cut from camp. Both are in New Orleans.